The present invention relates to a starch-based adhesive, and particularly a starch-based adhesive suitable for use in cigarette manufacturing.
Cigarettes are generally comprised of a cigarette rod and most often a filter or plug. The cigarette rod consists of an amount of tobacco wrapped in a paper tube, the paper tube being glued along one longitudinal edge with a suitable adhesive (side seam or lap seal). The filter or filter plug generally consists of crimped cellulose acetate tow treated with a plasticizer and wrapped into a cylindrical form with paper. The center of the paper is attached to the fibers using an adhesive (centerline adhesive) and the paper is then wrapped around the plug rod, overlapping and attaching itself with an adhesive (overlap adhesive) to form the cylindrical filter plug. The filter or plug is then attached to the cigarette rod by wrapping another paper (tipping paper) which contains an adhesive (tipping adhesive) around the plug and overlapping it with an aligned rod.
Typically the seam adhesives are applied via a nozzle of a high speed cigarette manufacturing machine. The equipment speed is typically greater than 5000 cigarettes per minute (cpm), and is often greater than 10,000 cigarettes per minute. At such production rates various properties of the adhesive such as viscosity, solids content and the setting speed become critical. In the past to overcome these obstacles, polyvinyl acetate (PVA) based adhesives have been used. Polyvinyl acetate based adhesives, however, are non-natural based adhesives.
There has been an increased interest in using natural-based adhesives. Exemplary natural-type adhesives include starch-based adhesives and gelatine adhesives. For example, U.S. Pat. No. 5,085,228 to Mooney et al. proposes an adhesive composition comprising a crosslinked starch and a fluidity or converted starch wherein the starches have an amylopectin content of at least about 70 percent by weight. U.S. Pat. No. 5,155,140 to Marten et al. proposes an adhesive mixture comprising 100 parts by weight of water, about 40 to about 120 parts by weight of gum arabic, about 3 to about 80 parts by weight of a starch selected from the group consisting of water-soluble starch degradation products, carboxymethyl starch (C.sub.6 H.sub.10 O.sub.5).sub.n, and gelatinized starch. U.S. Pat. No. 5,121,758 to Schmekel et al. proposes a glue made using pectins such as those obtained by the aqueous extraction of citrus fruit or apples.
There, however, continues to be a need for a natural-based adhesive that will satisfy the requirements of current cigarette manufacturing machines including satisfactory viscosity stability and machinability while not adversely affecting the properties of the cigarette itself.